Hammer for straightening saw-blades.



- No. 66l,| 98. Pa tented Nov..6, I900] J. w. & H. A. THUBSTON. HAMMERFOR ISTBAIGHTENING SAW BLADES.

(Application flledJMar. 19, 1900;)

(No Model.)

/WM Wm ment of a saw-blade.

in STATES PATENT GFFICE.

JAMES W. TI-IURSTON AND HERBERT A. THURSTON, OF INDIANAPOLIS, INDIANA.

HAMMER FOR STRAIGHTENING SAW-BLADES SPECIFICATION forming part ofLetters Patent No. 661,198, dated November 6, 1900.

Application filed March 19, 1900. Serial No. 9,307- (No model.)

To all whom, it may concern.-

Be it known that we, JAMES W. THURSTON and HERBERT A. THURSTON, citizensof the United States, residing at Indianapolis, in the county of Marionand State of Indiana, have invented new and useful Improvements inHammers for Straightening Saw-Blades, of which the following is aspecification.

This invention relates to the hammers which are employed in themanufacture of saws for straightening and planishing sawbladespreparatory to grinding their surfaces.

In the ordinary method of straightening saw-blades the same are hammeredupon an anvil by a hammer having a solid or unbroken striking-face, suchhammering being done either by hand or bya power-hammer for instance, atrip-hammer. Such a plainfaced hammer produces comparatively deepindentations in the metal and sometimes even cuts or fractures thesurface portions of the saw-blades,thus requiring considerable grindingof the surfaces of the blades to finish or smooth the same.

Our invention has for its object to provide an efficient hammer of thiskind which, while producing the desired result, makes comparativelyshallow indentations and avoids all liability of cutting or fracturingthe metal, thereby permitting the use of thinner sawblades andeconomizing in stock and also saving time and labor by requiring lessgrinding of the blades.

In the accompanying drawings, Figure 1 is a side elevation, partly insection, of a hammer embodying our invention, showing the same inconnection with an anvil and a frag- Fig. 2 is a plan view of thestriking-face of said hammer. Fig. 3 is a fragmentary vertical sectionof the hammer-head, on an enlarged scale, showing in an exaggeratedmanner the effect of a blow of the hammer upon the saw-blade. Figs. 4,5, and 6 are plan Views of the striking-face of the hammer, showingdifferent forms of the recess in the same.

Like letters of reference refer to like parts in the several figures.

A is an anvil such as is ordinarily used in straightening or planishingsaw-blades, and B is a saw-blade resting thereon.

thereof. the hammer with the recess 0 that portion of C is the head ofour improved hammer or tool. The striking-face c of the hammer isslightly convex or of suc'hform as to recede in all directions from itscentral portion.

0 is a recess or depression formed in the central portion of thestriking-face and ex tending a suitable distance into the head. Thisrecess is closed on all sides by the adjacent portion of thestriking-face, which lat ter recedes in all directions from the edge ofthe recess, so that this edge forms the most salient or highest portionof the strikingface.

In the use of the ordinary solid or unrecessed hammers heretoforeemployed the central or salient portion of the striking-face displacesthe metal of the saw-blade forwardly, as well as in other directions,and is liable to penetrate or indent the blade to such an extent as toout or fracture the surface portion By providing the striking-face ofthe face corresponding to the most salient portion of the ordinary solidhammer-head is cut away and only the salient metal forming the edge ofthe recess strikes the saw-blade and indents the same. Owing to thisconstruction, the penetrating capacity of the hammer is reduced withoutimpairing its efficiency. When the hammer strikes the saw-blade, thatportion of the blade directly opposite the recess of the hammer-head isnot spread or displaced, as is the case with the use of the or 'dinarysolid hammer, but remains in place,

as indicated in an exaggerated degree in Fig. 3.

By the use of this hammer saw-blades are straightened or planished withfewer blows than with the solid hammer-head and therefore in less time,and the indentations produced by the hammer are materially shallowerthan those made by the ordinary hammer, thus requiring less grinding ofthe straightened saw-blade to finish the same and permitting the use ofthinner blades without danger of cutting or fracturing the same. Animportant saving is thus efiected both in material and in the time andlabor involved in grinding down the uneven surface of the saw producedby hammering it.

The form of the recess in the hammerhead is immaterial. It is preferablycircular, as shown in Figs. 1 and 2 but it may, planishing' saw-blades,provided With a 0011 for instance, be oblong, square, or diamondvexstriking-face having a central recess or shaped, as shown in Figs. 4, 5,and 6. depression which is closed on all sides, snb- I5 We claim as ourinvention stant-ially as set forth.

5 1. A hammer or tool for straightening or Witness our hands this 10thday of March,

planishing saw-blades, provided in its strik- 1900. ins-face with arecess or depression which is r1 closed on all sides, and having thestrikingface formed to recede in all directions from to the edge of saidrecess, substantially as set Witnesses:

forth. JOHN PHIPPS,

2. A hammer or tool for straightening or TAYLOR E. GRONINGER;

